1. Field of the Invention
The present invention generally relates to systems for subsurface fluid drainage and storage, and more particularly, but not by way of limitation, to a subsurface drainage system and a drain structure therefor which promotes rapid infiltration of water through a subsoil structure.
2. Brief Description of Related Art
It is known that adequate drainage is a key to maintaining quality turf on athletic playing fields, such as football and soccer fields, baseball diamonds, golf courses, and the like. Further, well drained playing fields eliminate or significantly decrease the time during which heavy precipitation would make the field unuseable.
Previous efforts have been made in the field of subsurface drainage systems for sports fields and the like. In particular, U.S. Pat. No. 5,848,856 has been issued to William Bohnhoff. The Bohnhoff '856 patent discloses a subsurface drainage system that includes a base layer having a sloped surface and covered with an impermeable liner, a drainage collection pipe at the bottom of each sloped surface, an intermediate layer formed by a drain structure overlying the impermeable liner, a filter fabric layer, a root zone layer, and a turf. The drain structure is a thermoplastic mat with a laterally extensive backing grid having a plurality of intersecting struts defining grid openings therebetween and a plurality of spaced cylindrical support members projecting from the backing grid whereby fluid may flow through the backing grid and the cylindrical support member.
While use of the drainage structure described above has met with success, the transportation of such drain structures can be expensive, and its installation tedious and time consuming. In addition, the cylindrical support members are typically formed to have a planar lower edge that upon resting on the impermeable liner forms a fluid seal. It has been suggested to form openings in the sidewall that would promote drainage from the cylindrical support member, but the formation of such openings result in the creation of sharp edges that may cut or puncture the impermeable liner during the installation process or after the drain structure is covered with the turf and the soil that makes up the root zone layer. The present invention is directed to a subsurface drainage system and drain structure therefor that overcome the problems of the prior art.